ARM: dts: imx6sx-udoo-neo: enable i2c-2 and i2c-4 for onboard sensors

The i2c2 bus has a external plug which enables the easy connection of external
"bricks" with sensors of various kinds, while i2c4 on the Extended/Full boards
has a pair of on board motion sensors, accelerometer and magnetometer on one chip
and gyroscope on another so it makes sense to enable these i2c buses for use.
Tested on UDOO Neo Full.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>